The process of extracting DNA from a biological sample has many applications in biotechnology, for example, in methods of diagnosing diseases. Typically, the process of isolating and purifying DNA from a cell involves disrupting the cell membrane and removing contaminants that may interfere with the subsequent use of the isolated DNA.
Contaminants such as RNA and protein may be removed from a sample comprising DNA by enzymatic degradation. Although enzymes for the degradation of RNA or protein are known in the art and readily commercially available, reaction mixtures comprising both RNA-degrading and protein-degrading enzymes are not known and would be expected to lead to inactivation of the RNA-degrading enzyme by the protein-degrading enzyme.